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Managing pH: Aeroponics & Hydroponics

Written by Jared Anderson

September 18, 2019

pH is a key stat you’ll need to monitor for your soilless garden. Managing your pH will ensure your plants are able to absorb all the nutrients made available to them. So, what should the pH level be for your Aeroponics or Hydroponics system?

The ideal pH range for your hydroponics and aeroponics systems is between 5.7 and 6.3. Keeping your pH within this range will ensure your plants have the ability to absorb all the nutrients available to them.

What Is pH?

In short, pH is a measurement of the acidity or alkalinity of your nutrient solution (or really any given solution). The pH scale ranges from 0 – 14. Anything between 0-6 is acidic, with 0 being the most acidic. A reading of 7 is considered neutral. Anything 8-14 is considered basic, with 14 being the most alkaline.

How Do I Test My Hydroponics System’s pH?

Manual Liquid Test Kit:

You can easily test the pH of your nutrient solution with a simple three-part kit. This method is highly accurate and one of the most popular methods. Most of the kits will include a concentrated solution to increase the pH and one to decrease the pH. It will also include a pH sensitive dye you’ll mix into a clean sample of your nutrient solution.

A few drops of the pH sensitive dye are added to the water in the provided vile. Once the specified amount of drops have been added, put the lid on the vile then shake to mix them together. Depending on the color the water turns will reflect the pH of the water. The kit will provide a key with the different colors to determine the pH of your solution.

Litmus Test Strips:

Litmus test strips are one method of checking the pH of your solution. The strips have a reactive coating that when dipped into a sample of your nutrient solution, the coating will change colors to reflect the pH of your solution. These samples have been found to be less accurate than the liquid test method as described above.

Handheld Meters and Constant Monitoring Systems

There are a multitude of different handheld pH meters that you can use to manually test the pH of your system.. Another type is one that is constantly monitoring the pH. These are more common in large scale systems. As one might imagine these types of pH monitoring systems are far more costly than the first two options. Both the handheld meter and daily monitoring system both have to be periodically calibrated with a manual system to ensure the reading are accurate.

How Often Should I Check My pH?

Depending on the size of your reservoir (and your level of OCDness) will really determine how often you should be checking your pH. Smaller reservoirs are prone to much larger swings in pH. Therefore it’s recommended you check the pH at least every other day if not daily. You should create a spreadsheet where you log the pH level of your system. If you start noticing it trending in the wrong direction, this could be a sign there’s something off with your system.

How Do I Lower The pH Of My Hydroponics System?

To lower the pH of your nutrient solution you’ll need to add food grade Phosphoric acid. You’ll want to add a little at a time and give it time to mix fully, then measure the pH again. You’ll need to repeat this process until you get your pH into the ideal zone.

How Do I Raise The pH Of My Hydroponics System?

To raise the pH of your nutrient solution you’ll need to add a food grade Base solution, commonly made of Potassium Hydroxide and Potassium Carbonate. Make sure to only add a little bit of the solution, gradually working up to the desired level. No matter if your system runs high or low, you never want to overshoot on the far end of the range. 

For example: We test the pH of our system and it tests at 8.0. We need to add pH down (acid) to our system. Based on our source water (city water, well water, rain water, etc.) a fresh batch of nutrient solution always starts out more Base. Therefore, we will never (unless something drastically changes to our source water) use pH up in our system.

Conclusion

With soilless gardening methods like hydroponics and aeroponics, pH is one key variable that you must keep a close eye on to ensure the health of your garden.  Because your working with different chemicals (like acid) it’s important to wear protective gloves, eyewear.

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